Maitri (Maitrāyaṇīya) Upaniṣad 6.31

6.31

kimātmakāni vā etānīndriyāṇi pracarantyudgantā caiteṣāmiha ko niyantā vetyāha | pratyāhātmātmakānītyātmā hyeṣāmudgantā vāpsaraso bhānavīyāśca marīcayo nāma atha pañcabhiḥ raśmibhirviṣayānatti katama ātmeti yo'yaṃ śuddhaḥ pūtaḥ śūnyaḥ śāntādilakṣaṇoktaḥ svakairliṅgairupagṛhyaḥ tasyaitalliṅgamaliṅgasyāgneryadauṣṇyamāviṣṭaṃ cāpāṃ yaḥ śivatamorasa ityeke | atha vākṣrotraṃ cakṣurmanaḥ prāṇa ityeke, atha buddhirdhṛtiḥ smṛtiḥ prajñā tadityeke atha te etasyaivaṃ yathaiveha bījasyāṅkurāvāthadhūmārcirviṣphuliṅgā ivāgneśceti atrodāharanti vahneśca yadvatkhalu viṣphuliṅgāḥ sūryānmayūkhāśca tathaiva tasya |
prāṇādayo vai punareva tasmā-dabhyuccarantīha yathākrameṇa ||

31. Of what nature, verily, are these senses that range forth? And who is the one here who goes forth and restrains them?—Thus has it been said.

The answer is: ‘They are of the nature of soul (*ātmaka*), for the soul is he who goes forth and restrains them. There are enticing objects of sense (*apsaras*), and there are so-called luminous rays. With his five rays he feeds upon objects (*viṣaya*).’

‘Which soul?’

‘He who has been described as “pure, clean, void, tranquil, and of other marks.” He is to be apprehended by his own peculiar marks.

Some say that the mark of Him who is without any mark is what heat and [anything] pervaded by it is to fire, and what a most agreeable taste is to water.

Now others say it is speech, hearing, sight, mind, breath; now others that it is intellect, steadfastness, memory,

intelligence. Now, verily, these are the marks of Him, even as sprouts here are the mark of a seed, as smoke, light, and sparks are the marks of a fire. On this point they quote :—

And as, indeed, from fire the sparks do issue,
And likewise, too, from out the sun its light-rays,
From It repeatedly all breathing creatures
Come forth into this world, each in its order.